Stability of vacuolar betaxanthin pigments in juices from Moroccan yellow Opuntia ficus indica fruits

Pigment stability of yellow juices prepared from Moroccan cactus pear (Opuntia ficus indica) was determined as a function of temperature and pH. The experiments were carried out at temperatures ranging from 80 to 100 °C with juices at pH 3.5, 5 and 6.5. The degree of pigment retention decreased when the temperature increased. The degradation constant rates were determined for thermal degradation rates of pseudo-first order. The Arrhenius plot obtained for the degradation of betaxanthin from the yellow fruits was not linear. Regardless of the temperature treatment, the lowest degradation was obtained for pH 5. Where some stabilizers were tested for the protection of pigments, the results showed that ascorbic acid was a better protective agent at pH 3.5, increasing the protection by 40%.